This invention relates generally to electric machines, and more specifically, to methods for fabricating a wedge system that may be used with electric machines.
Generally, known electric machines use a rotor that includes at least one conducting coil retained therein. Known conducting coils are typically retained within a cavity formed within the rotor. As the rotor rotates, the conductor coil conducts an electric current that operates the machine. At least some known, rotors include a wedge that is positioned within the cavity to retain the conductor coil in position. Because the wedge is in the cavity, the wedge is subjected to centrifugal forces due to coil and wedge inertia as the rotor rotates. As the wedge is held in the cavity the centrifugal forces are transferred to the rotor. Over time, the wedge and the rotor will be subjected to cyclic loading due to starting and stopping of the machine. This may cause fatigue failure of the wedge and/or the rotor, thereby causing the conductor coil to become displaced from the cavity.
To prevent the conductor coil from becoming displaced, at least some known wedges are fabricated from a material that has an increased weight in comparison to the coil. However, the added weight may reduce the overall performance of the machine. Moreover, at least some rotors are designed with fewer and/or smaller conductor coils positioned within the cavity. The combination of the added weight and the reduced coil size may also result in a reduction of the machine's performance. To compensate for the decreased performance, at least some machines are fabricated with an increased length to maintain machine efficiency. As a result, costs, fabrication time, and/or maintenance associated with the machine may be increased. In addition, applicable uses for the machine may also be limited due to the machine's size.